Image Sensor Organic Silicon Stacked Layer Design
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Solution Overview
Problem
Silicon photodiodes in image sensors face challenges with small pixel size leading to decreased sensitivity due to reduced absorption area, and the process of replacing them with organic photoelectric devices becomes complex with increased light loss.
Innovation Solution
An image sensor design featuring a semiconductor substrate with a first and second light-transmitting electrode forming an organic photoelectric device, where the first photo-sensing device senses light in a longer wavelength region and the second in a shorter wavelength region, with an organic photoelectric conversion layer absorbing light in a different wavelength region, and a selectively transmitting region to enhance light absorption and reduce light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is decreased to achieve high resolution, then the resolution is improved, but the sensitivity is decreased due to reduced absorption area
Solution Approach 1:
The patent transitions from a planar 2D photodiode structure to a 3D stacked structure with multiple photoelectric conversion layers positioned at different depths. This vertical stacking allows each layer to capture light at different wavelengths simultaneously, effectively increasing the total light absorption area without increasing the horizontal pixel footprint, thus maintaining high resolution while improving sensitivity
Solution Approach 2:
The patent employs composite material structures by combining multiple photoelectric conversion layers with different spectral response characteristics (silicon photodiode for blue light, organic photodiode for green light, and another silicon photodiode for red light) into a single integrated pixel. This composite approach enables each material to absorb light in its optimal wavelength range, maximizing overall light absorption efficiency within the constrained pixel area
2Reliability
If an organic photoelectric device is used to replace silicon photodiode, then the absorption area is increased, but the process becomes complicated and light loss increases
Solution Approach 1:
The patent merges the organic photoelectric conversion layer with the existing silicon photodiode structure into a single integrated stacked configuration. The organic layer is positioned directly above the silicon photodiode without requiring separate complex interconnection structures, allowing both materials to work together in capturing different wavelength ranges while simplifying the overall device architecture and reducing process complexity
Solution Approach 2:
The stacked photoelectric conversion structure serves multiple functions simultaneously: the upper organic photodiode captures green light while the lower silicon photodiode captures blue or red light, and both layers contribute to overall light absorption. This multi-functional design eliminates the need for separate dedicated sensors for different wavelengths, simplifying the device structure and reducing manufacturing complexity
3Measurement precision
If additional insulation or color filter layers are added to improve wavelength separation, then the color separation is improved, but the device size increases and light loss increases
Solution Approach 1:
The patent achieves wavelength separation by positioning different photoelectric conversion layers at different vertical depths within the pixel structure, rather than using horizontal color filter layers. The upper organic photodiode absorbs green light before it can reach the lower silicon photodiode, which captures blue or red light. This vertical stratification provides effective wavelength discrimination without increasing the horizontal device footprint or requiring additional lateral space for color filters
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a smaller size image sensor with reduced light loss and simplified process, improving sensitivity and color separation characteristics without the need for additional insulation or color filter layers.
Implementation Method 1
An organic photoelectric conversion layer, positioned on one side of the semiconductor substrate and configured to absorb light in a third wavelength region
Implementation Method 2
a first photo-sensing device sensing light in a first wavelength region and a second photo-sensing device sensing light in a second wavelength region
Implementation Method 3
The selectively transmitting region may selectively transmit light in the first wavelength region and may selectively reflect or absorb light in the second wavelength region
Data Source
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AI summary
Example embodiments relate to an image sensor that includes a semiconductor substrate integrated with at least one photo-sensing device, an impurity-doped first light-transmitting electrode present in the semiconductor substrate, an organic photoelectric conversion layer positioned on one side of the semiconductor substrate and absorbing light in a different wavelength from the wavelength sensed by the photo-sensing device, and a second light-transmitting electrode positioned on one side of the organic photoelectric conversion layer, and an electronic device including the same.